Re: [edk2-devel] [PATCH v10 06/46] MdePkg/BaseLib: Add support for the XGETBV instruction

[Lendacky, Thomas]

On 7/15/20 11:17 AM, Tom Lendacky wrote:
On 7/15/20 10:55 AM, Laszlo Ersek wrote:
Hi Tom,
On 07/14/20 16:27, Lendacky, Thomas wrote:
From: Tom Lendacky <thomas.lenda...@amd.com>

BZ: 
https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbugzilla.tianocore.org%2Fshow_bug.cgi%3Fid%3D2198&amp;data=02%7C01%7Cthomas.lendacky%40amd.com%7C00c7f97271bf4efd050608d828d79a13%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637304253757199823&amp;sdata=hQ%2BP%2F5DintrtGi66sfqRI%2B9h4V1rTB1YlYdY1VX6sLM%3D&amp;reserved=0

Under SEV-ES, a CPUID instruction requires the current value of the XCR0
register. In order to retrieve that value, the XGETBV instruction needs
to be executed.

Provide the necessary support to execute the XGETBV instruction.

Cc: Michael D Kinney <michael.d.kin...@intel.com>
Cc: Liming Gao <liming....@intel.com>
Signed-off-by: Tom Lendacky <thomas.lenda...@amd.com>
---
  MdePkg/Library/BaseLib/BaseLib.inf      |  2 ++
  MdePkg/Include/Library/BaseLib.h        | 17 +++++++++++++
  MdePkg/Library/BaseLib/Ia32/GccInline.c | 28 ++++++++++++++++++++
  MdePkg/Library/BaseLib/X64/GccInline.c  | 30 ++++++++++++++++++++++
  MdePkg/Library/BaseLib/Ia32/XGetBv.nasm | 31 ++++++++++++++++++++++
  MdePkg/Library/BaseLib/X64/XGetBv.nasm  | 34 +++++++++++++++++++++++++
  6 files changed, 142 insertions(+)
  create mode 100644 MdePkg/Library/BaseLib/Ia32/XGetBv.nasm
  create mode 100644 MdePkg/Library/BaseLib/X64/XGetBv.nasm

This patch no longer applies, it conflicts with commit d3c9e40abcc8
("MdePkg/BaseLib: Break out IA32/X64 GCC inline privileged functions",
2020-07-15).

Ok, that looks like it landed just after I sent my patches.


The conflict persists if I successfully apply the series on c7195b9ec3c5
-- just preceding Mike's series "[Patch v3 00/16] UnitTestFrameworkPkg:
Enhancements and bug fixes" --, and then try to rebase to current master
(e77966b341b9) from there.

Can you please investigate?

Yup, I'll take a look.

Ok, after rebasing, the GccInline.c split caused the conflict and has been 
resolved.

There was also an added PCD that conflicted with one of mine that needed 
updating.

I'll send out a new version today or Monday.

Thanks,
Tom


Thanks,
Tom


Thanks,
Laszlo


diff --git a/MdePkg/Library/BaseLib/BaseLib.inf 
b/MdePkg/Library/BaseLib/BaseLib.inf
index a57ae2da31f3..da6bc22a3e2b 100644
--- a/MdePkg/Library/BaseLib/BaseLib.inf
+++ b/MdePkg/Library/BaseLib/BaseLib.inf
@@ -153,6 +153,7 @@ [Sources.Ia32]
    Ia32/ARShiftU64.c | MSFT
    Ia32/EnableCache.c | MSFT
    Ia32/DisableCache.c | MSFT
+  Ia32/XGetBv.nasm | MSFT
  
  
    Ia32/GccInline.c | GCC
@@ -287,6 +288,7 @@ [Sources.X64]
    X64/ReadCr2.nasm| MSFT
    X64/ReadCr0.nasm| MSFT
    X64/ReadEflags.nasm| MSFT
+  X64/XGetBv.nasm | MSFT
  
  
    X64/Non-existing.c
diff --git a/MdePkg/Include/Library/BaseLib.h b/MdePkg/Include/Library/BaseLib.h
index 8e7b87cbda4e..7edf0051a0a0 100644
--- a/MdePkg/Include/Library/BaseLib.h
+++ b/MdePkg/Include/Library/BaseLib.h
@@ -7831,6 +7831,23 @@ AsmLfence (
    VOID
    );
  
+/**
+  Executes a XGETBV instruction
+
+  Executes a XGETBV instruction. This function is only available on IA-32 and
+  x64.
+
+  @param[in] Index        Extended control register index
+
+  @return                 The current value of the extended control register
+**/
+UINT64
+EFIAPI
+AsmXGetBv (
+  IN UINT32  Index
+  );
+
+
  /**
    Patch the immediate operand of an IA32 or X64 instruction such that the 
byte,
    word, dword or qword operand is encoded at the end of the instruction's
diff --git a/MdePkg/Library/BaseLib/Ia32/GccInline.c 
b/MdePkg/Library/BaseLib/Ia32/GccInline.c
index 5287200f8754..c962bcfa4617 100644
--- a/MdePkg/Library/BaseLib/Ia32/GccInline.c
+++ b/MdePkg/Library/BaseLib/Ia32/GccInline.c
@@ -1763,3 +1763,31 @@ AsmFlushCacheLine (
  }
  
  
+/**
+  Executes a XGETBV instruction
+
+  Executes a XGETBV instruction. This function is only available on IA-32 and
+  x64.
+
+  @param[in] Index        Extended control register index
+
+  @return                 The current value of the extended control register
+**/
+UINT64
+EFIAPI
+AsmXGetBv (
+  IN UINT32 Index
+  )
+{
+  UINT64 Data;
+
+  __asm__ __volatile__ (
+    "xgetbv"
+    : "=A" (Data)
+    : "c"  (Index)
+    );
+
+  return Data;
+}
+
+
diff --git a/MdePkg/Library/BaseLib/X64/GccInline.c 
b/MdePkg/Library/BaseLib/X64/GccInline.c
index 154ce1f57e92..915555198f9f 100644
--- a/MdePkg/Library/BaseLib/X64/GccInline.c
+++ b/MdePkg/Library/BaseLib/X64/GccInline.c
@@ -1798,3 +1798,33 @@ AsmFlushCacheLine (
  }
  
  
+/**
+  Executes a XGETBV instruction
+
+  Executes a XGETBV instruction. This function is only available on IA-32 and
+  x64.
+
+  @param[in] Index        Extended control register index
+
+  @return                 The current value of the extended control register
+**/
+UINT64
+EFIAPI
+AsmXGetBv (
+  IN UINT32 Index
+  )
+{
+  UINT32 LowData;
+  UINT32 HighData;
+
+  __asm__ __volatile__ (
+    "xgetbv"
+    : "=a" (LowData),
+      "=d" (HighData)
+    : "c"  (Index)
+    );
+
+  return (((UINT64)HighData) << 32) | LowData;
+}
+
+
diff --git a/MdePkg/Library/BaseLib/Ia32/XGetBv.nasm 
b/MdePkg/Library/BaseLib/Ia32/XGetBv.nasm
new file mode 100644
index 000000000000..9f7b03bbff35
--- /dev/null
+++ b/MdePkg/Library/BaseLib/Ia32/XGetBv.nasm
@@ -0,0 +1,31 @@
+;------------------------------------------------------------------------------
+;
+; Copyright (C) 2020, Advanced Micro Devices, Inc. All rights reserved.<BR>
+; SPDX-License-Identifier: BSD-2-Clause-Patent
+;
+; Module Name:
+;
+;   XGetBv.Asm
+;
+; Abstract:
+;
+;   AsmXgetBv function
+;
+; Notes:
+;
+;------------------------------------------------------------------------------
+
+    SECTION .text
+
+;------------------------------------------------------------------------------
+; UINT64
+; EFIAPI
+; AsmXGetBv (
+;   IN UINT32  Index
+;   );
+;------------------------------------------------------------------------------
+global ASM_PFX(AsmXGetBv)
+ASM_PFX(AsmXGetBv):
+    mov     ecx, [esp + 4]
+    xgetbv
+    ret
diff --git a/MdePkg/Library/BaseLib/X64/XGetBv.nasm 
b/MdePkg/Library/BaseLib/X64/XGetBv.nasm
new file mode 100644
index 000000000000..09f3be8ae0a8
--- /dev/null
+++ b/MdePkg/Library/BaseLib/X64/XGetBv.nasm
@@ -0,0 +1,34 @@
+;------------------------------------------------------------------------------
+;
+; Copyright (C) 2020, Advanced Micro Devices, Inc. All rights reserved.<BR>
+; SPDX-License-Identifier: BSD-2-Clause-Patent
+;
+; Module Name:
+;
+;   XGetBv.Asm
+;
+; Abstract:
+;
+;   AsmXgetBv function
+;
+; Notes:
+;
+;------------------------------------------------------------------------------
+
+    DEFAULT REL
+    SECTION .text
+
+;------------------------------------------------------------------------------
+; UINT64
+; EFIAPI
+; AsmXGetBv (
+;   IN UINT32  Index
+;   );
+;------------------------------------------------------------------------------
+global ASM_PFX(AsmXGetBv)
+ASM_PFX(AsmXGetBv):
+    xgetbv
+    shl     rdx, 32
+    or      rax, rdx
+    ret
+



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